Not cynical - just supply and demand and needing to make a profit. It's the way business has worked for at least 2000 years. The PIs and Travelodges of the world are subject to the same market forces as your local corner shop. But they are more resilient.
We stay in Lewes regularly. COVID killed two or three locally owned hotels. It didn't kill Premier Inn and it didn't kill the amateur AirBnBers who use the summer season for a bit of extra income.
No - it's reduced demand = reduced cost.
Yes - increased demand because of a concert.
Yes - increased demand because of a major international event.
At most that's a local factor, despite what the Daily Mail might claim. There are about 50,000 asylum seekers in "hotel" rooms (actually more likely to be the sort of grotty "B&B" rooms used for homeless families). PI alone has more bedrooms than that - and you can bet they're being housed at 3 or 4 to the room.
Out of deference to a nonpolitical forum I won't go further...
I think you mean "one rich landowner has spoiled it for the many".
By booking ahead and being flexible it's sometimes still possible to get a decent rate. I paid £100 a few weeks ago for a
Travelodge in Forest Green (a few stops from KX) and I've got a Farringdon PI in a few weeks for the same price.